Field of the Disclosure
The technology of the disclosure relates to surgical screwdriver devices and related assemblies and methods for creating and removing pedicle screw attachments with vertebrae.
Technical Background
A vertebral column and a spinal cord of a patient extend from the skull to the pelvis and form a longitudinal axis of a patient. The column includes vertebra that are separated by fibrocartilage structures (intervertebral disks) that are interconnected with ligaments. The vertebral column protects the spinal cord and provides structural support for the patient. The spinal cord along with a bundle of nerve fibers extending from the spinal cord form a central nervous system enabling communication between the brain and other parts of the body of the patient. The spinal cord is protected by being disposed through a vertebral canal formed by openings in each of the vertebrae. The vertebral column typically facilitates movement of the patient by enabling relative movement between adjacent vertebrae and often serves its functions without issues.
Abnormalities may occur to the vertebral column necessitating medical intervention. In one example, one or more portions of the vertebral column may have abnormalities from development issues and/or trauma making relative movement at these locations problematic. Medical intervention may be necessary to stop relative movement at these locations. Types of exemplary abnormalities include degenerative disc disease, spondylolisthesis, trauma, deformities, tumors, stenosis, and pseudoarthrosis (earlier failed spine surgery). Pain may be lessened and/or opportunities for healing may occur once relative movement is prevented.
Conventional spine fusion is one surgical approach for permanently or temporarily immobilizing adjacent vertebrae relative to each other. In this approach, fasteners (e.g., pedicle screws) are attached to the adjacent vertebrae to serve as anchor points, and these anchor points are interconnected with at least one immobilizing rod to stop relative movement between the adjacent vertebrae. Conventionally an attending surgeon typically attaches the pedicle screws to the vertebrae by screwing these pedicle screws into the adjacent vertebrae with a surgical screwdriver. The desired trajectory of each screw into the desired vertebra is carefully selected to avoid damage to the spinal cord and nerve fibers extending therefrom between vertebrae. The desired trajectory is also selected to achieve a stable and strong attachment between the screw and the vertebrae. The advantage to achieving a strong pedicle screw attachment to the vertebra is that the adjacent vertebrae are immobilized with respect to each other when the interconnection rod is connected to the pedicle screws.
Inserting and retracting the pedicle screw into and from the vertebrae is difficult, because it is a physically demanding task for the surgeon and requires precision to avoid inflicting nerve injuries to the patient. Specifically, surgeons have traditionally utilized manual screwdrivers to ensure that the screws are inserted precisely along the desired trajectory and that the final position of the screw results in a strong attachment. The proximity of the desired trajectory of the pedicle screw to the spinal cord and spinal nerves makes it imperative to precisely follow the desired trajectory and the manual screwdrivers can provide the precision and heightened feedback desired by the surgeon.
The manual screwdriver also requires the surgeon to manually apply a relatively high torque, which when applied, can be easily monitored by the surgeon to understand whether a strong pedicle screw attachment has been achieved. However, manually applying a high torque to gain precision is gained at the expense of repetitive motion injuries (e.g., lateral epicondylitis) suffered by many attending surgeons.
Attempts have been made to reduce surgeon fatigue and injury by replacing the manual screwdrivers used for pedicle screw insertion with power screwdrivers developed for use in the building construction industry and modified to have higher torque to insert pedicle screws into vertebrae. Although the objective of power screwdrivers may have reduced surgeon fatigue and the likelihood of repetitive use injuries, these power screwdrivers offer less sensitive tactile feedback to the surgeon during screw insertion than with manual surgical screwdrivers. In some cases users have reported “zero feel” as to feedback regarding the strength of the pedicle screw attachment when using the power screwdrivers. Thus, conventional power screwdrivers used with pedicle screws have merely become power screwdrivers from the building construction industry modified for surgery without meeting special medical requirements. The end result is that it is difficult with power screwdrivers originally designed for the building construction industry to ensure that the pedicle screw attachment with the vertebra is strong and stable and that injury to the patient is avoided. Similar challenges occur if and when the pedicle screw is removed from the vertebra. Accordingly new approaches are needed to manage pedicle screw attachments with vertebra, so that strong and stable attachments are achieved without injury to patients and surgeons.